Centrifuge tests on lateral bearing behaviors of double steel sheet pile structures on marine soft grounds

Abstract

Centrifuge tests were conducted to reveal the lateral bearing behaviors of double steel sheet pile structures (DSSPSs). The model ground was made of Kaolin clay in a rectangular model container, and two DSSPS models with different widths were employed to separately resist lateral loading. The motion modes, load and displacement relations, pore and soil pressures, structural strains, and pile bending moments were emphasized by means of comparative analysis. Results show that the DSSPS moved downward and forward with increasing lateral loads, more rotation and less sliding governed the failure mechanism. The ultimate lateral bearing loads increased by 23.4% using an elastic-plastic intersection criterion when the width of the DSSPS ranged from 4 m to 8 m, but the wide DSSPS showed a strong size effect in the dimensionless form. The soil pressures on the loading side exhibited parabola distributions to generate upper active and lower passive zones, whereas the soil pressures generally exhibited decreasing tendencies on the unloading side to generate upper passive and lower active zones, and different rotational center elevations for wide and narrow DSSPSs were derived. Negative pore pressures occurred on the loading sides of wide and narrow DSSPSs due to the structure-soil tension, but pore pressure tendencies differed evidently on the unloading sides influenced by the different rotational centers. The pile strains reflected larger values between the upper and lower tie rods than other areas, and strains of the upper tie rod of the wide DSSPS became larger with increasing lateral loads. Bending moments of sheet pile walls of wide and narrow DSSPSs differed evidently around the seabed and their magnitudes became larger with increasing lateral loads, whereas the bending moment magnitudes were almost zero around wall toes.